Text by Stefan Krause
On this night 25 years ago, one of the most significant geomagnetic events occurred.
The cause was an X4 category flare in AR 5395, which occurred on 10.03.1989 between 18:58 and 19:22 UT. The related CME reached Earth on 13.03.89 at 01:27 UT after about 54 hours of travel time. At that moment, one of the strongest geomagnetic storms ever observed began. It was not as extreme as the Carrington Event of 1859, but it surpassed the Bastille Day Event in July 2000 and the Halloween storms of 2003 by far. The geomagnetic storm of 1989 lasted about 48 hours, with the Kp value remaining at 9 until 14.03.13. The most well-known but not the only "side effect" of this event was a 9-hour power outage in Quebec. It was caused by currents induced in the high voltage lines. This incident demonstrated the vulnerability of our technical infrastructure to solar events and triggered a research boom in space weather and solar-terrestrial relationships that continues to this day.
A more pleasant side effect of this geomagnetic superstorm was intense and colorful auroras over Europe and North America, which were visible as far south as Florida.
